Hydrogen bonding stabilizes globular proteins

It is clear that intramolecular hydrogen bonds are essential to the structure and stability of globular proteins. It is not clear, however, whether they make a net favorable contribution to this stability. Experimental and theoretical studies are at odds over this important question. Measurements of the change in conformational stability, delta (delta G), for the mutation of a hydrogen bonded residue to one incapable of hydrogen bonding suggest a stabilization of 1.0 kcal/mol per hydrogen bond. If the delta (delta G) values are corrected for differences in side-chain hydrophobicity and conformational entropy, then the estimated stabilization becomes 2.2 kcal/mol per hydrogen bond. These and other experimental studies discussed here are consistent and compelling: hydrogen bonding stabilizes globular proteins.     

Incidence of symptomatic urinary tract infections in HIV seropositive patients and the use of cotrimoxazole as prophylaxis against Pneumocystis carinii pneumonia

A case of complete synostosis of the cervical spine in a 12-year-old girl is described. Differential diagnosis included dysontogenetic forms of synostosis, Klippel-Feil syndrome, rheumatic synostosis and synostosis of other inflammatory origin. This severe case, the first of its type to be described, appeared to be due to tuberculosis of the cervical spine.     

Curcumin induces apoptosis in immortalized NIH 3T3 and malignant cancer cell lines

Curcumin, which is a widely used dietary pigment and spice, has been demonstrated to be an effective inhibitor of tumor promotion in mouse skin carcinogenesis. We report that curcumin induces cell shrinkage, chromatin condensation, and DNA fragmentation, characteristics of apoptosis, in immortalized mouse embryo fibroblast NIH 3T3 erb B2 oncogene-transformed NIH 3T3, mouse sarcoma S180, human colon cancer cell HT-29, human kidney cancer cell 293, and human hepatocellular carcinoma Hep G2 cells, but not in primary culture of mouse embryonic fibroblast C3H 10T1/2, rat embryonic fibroblast, and human foreskin fibroblast cells in a concentration- and time-dependent manner. Many cellular and biochemical effects of curcumin in mouse fibroblast cells have been reported, such as inhibition of protein kinase C (PKC) activity induced by phorbol 12-myristate 13-acetate treatment, inhibition of tyrosine protein kinase activity, and inhibition of arachidonic acid (AA) metabolism. Treatment of NIH 3T3 cells with the PKC inhibitor staurosporine, the tyrosine kinase inhibitor herbimycin A, and the AA metabolism inhibitor quinacrine induces apoptotic cell death. These results suggest that, in some immortalized and transformed cells, blocking the cellular signal transduction might trigger the induction of apoptosis.     

Use of acetabular models in planning complex acetabular reconstructions

The number of patients requiring revision total hip arthroplasty continues to increase each year. Accurate preoperative planning is a key factor in obtaining a good result. Radiographs provide little information concerning the actual extent of the acetabular defects. Computed tomography-generated models of the acetabulum can provide the surgeon with accurate information concerning the size and location of the defects. Evaluation of radiographs and models in 24 cases showed that radiographs alone failed to detect all 13 anterior wall defects (P < .001), 8 of 18 posterior wall defects (44.4%, P < .001), and 8 of 19 segmental central defects (42%, P < .001), all of which were easily identified with the models. This study showed that preoperative planning based on the foam models accurately predicted the actual implant used in 22 of 24 cases (92%).     

A gene at 59 minutes on the Escherichia coli chromosome encodes a lipoprotein with unusual amino acid repeat sequences

We report a 1.432-kb DNA sequence at 59 min on the Escherichia coli chromosome that connects the published sequences of the pcm gene for the isoaspartyl protein methyltransferase and that of the katF or rpoS (katF/rpoS) gene for a sigma factor involved in stationary-phase gene expression. Analysis of the DNA sequence reveals an open reading frame potentially encoding a polypeptide of 379 amino acids. The polypeptide sequence includes a consensus bacterial lipidation sequence present at residues 23 to 26 (Leu-Ala-Gly-Cys), four octapeptide proline- and glutamine-rich repeats of consensus sequence QQPQIQPV, and four heptapeptide threonine- and serine-rich repeats of consensus sequence PTA(S,T)TTE. The deduced amino acid sequence, especially in the C-terminal region, is similar to that of the Haemophilus somnus LppB lipoprotein outer membrane antigen (40% overall sequence identity; 77% identity in last 95 residues). The LppB lipoprotein binds Congo red dye and has been proposed to be a virulence determinant in H. somnus. Utilizing a plasmid construct with the E. coli gene under the control of a phage T7 promoter, we demonstrate the lipidation of this gene product by the incorporation of [3H]palmitic acid into a 42-kDa polypeptide. We also show that treatment of E. coli cells with globomycin, an inhibitor of the lipoprotein signal peptidase, results in the accumulation of a 46-kDa precursor. We thus designate the protein NlpD (new lipoprotein D). E. coli cells overexpressing NlpD bind Congo red dye, suggesting a common function with the H. somnus LppB protein. Disruption of the chromosomal E. coli nlpD gene by insertional mutagenesis results in decreased stationary-phase survival after 7 days.     

CDK4 down-regulation induced by paclitaxel is associated with G1 arrest in gastric cancer cells

Paclitaxel induces a cell cycle block at G2-M phase by preventing the depolymerization of microtubules and induces p53-independent apoptosis in many cancer cells. We observed that gastric cancer cells treated with paclitaxel have shown a cyclin-dependent kinase (CDK)4 down-regulation. This paclitaxel-induced CDK4 down-regulation resulted in a cell cycle arrest at G1-S phase. To confirm this observation, we prepared stable transfectants that overexpressed CDK4 and analyzed the cell cycle progression. Ectopic expression of CDK4 in SNU cells resulted in a release of paclitaxel-induced G1 arrest. The release of G1 arrest by enforced expression of CDK4 seems to make the cells more sensitive to paclitaxel-induced apoptosis. From this finding, we could then suggest that paclitaxel treatment induces both G1-S and G2-M blocks in the cell cycle progression of gastric cancer cells.     

Management of bronchobiliary fistula as a late complication of hepatic resection

Bronchobiliary fistula is an uncommon but remarkable complication after hepatic resection. The case reported illustrates the clinical presentation and preferred initial management of these fistulae. A 61-year-old white male underwent two wedge resections for colorectal metastases to the liver with removal of a portion of the right diaphragm. Four years later, he developed obstructive jaundice secondary to tumor recurrence in the porta hepatis, which required endoscopic stent placement, radiation, and chemotherapy. Almost 2 years later, he developed frank biliptysis. Percutaneous transhepatic cholangiography (PTC) revealed occlusion of the common hepatic duct stent and a bronchobiliary fistula. With adequate reestablishment of common duct drainage, the patient rapidly improved and was discharged free of symptoms. Bronchobiliary fistulae are rare complications of hepatic resection that can present from days to years after operation. Endoscopic retrograde cholangiopancreatography and PTC are the diagnostic studies of choice and offer the possibility of therapeutic intervention. Although large series in the literature emphasize the surgical management of bronchobiliary fistulae, the reoperative procedures tend to be complicated, with a significant morbidity and mortality. Nonsurgical interventions via endoscopic retrograde cholangiopancreatography or PTC are more recently notably successful when resolution of a distal biliary obstruction is accomplished. Only after aggressive attempts at nonoperative, interventional techniques have failed should operative approaches be entertained.     

The effect of alpha-tocopherol and beta-carotene supplementation on COPD symptoms

The effects of alpha-tocopherol (50 mg/d) and beta-carotene (20 mg/d) supplementation on symptoms of chronic obstructive pulmonary disease were studied among the 29,133 participants of the Alpha-Tocopherol Beta-Carotene Cancer Prevention Study undertaken to investigate the effects of these two substances in the prevention of lung and other cancers. During the follow-up the supplementations did not affect the recurrence or incidence of chronic cough, phlegm, or dyspnea. The prevalence of chronic bronchitis and dyspnea at baseline was lower among those with high dietary intake of beta-carotene (OR = 0.78 and 0.67, respectively) or vitamin E (OR = 0.87 and 0.77) and high serum beta-carotene (OR = 0.59 and 0.62) and alpha-tocopherol (OR = 0.76 and 0.82). High intake and serum levels of retinol were associated with low prevalence of dyspnea (OR = 0.84 and 0.80, respectively) but not with chronic bronchitis. The results indicate no benefit from supplementation with alpha-tocopherol or beta-carotene on the symptoms of chronic obstructive pulmonary disorders but support the beneficial effect of dietary intake of fruits and vegetables rich in these compounds.     

Relationship between feed withdrawal and viscera condition of broilers

An AIDS patient with disseminated histoplasmosis who improved during treatment with fluconazole but remained fungemic and subsequently relapsed is described. Isolates obtained from blood during therapy showed a progressive increase in fluconazole MIC from 0.625 to 20 micrograms/ml. The pretreatment, or parent, isolate and the posttreatment, or relapse, isolate demonstrated identical genetic patterns by PCR fingerprinting with three different primers. Fluconazole was less potent inhibitor of the growth of the relapse isolate than of the pretreatment isolate (50% inhibitory concentration [IC50] = 11.7 microM), while itraconazole was more potent (relapse isolate IC50 = 0.0011 microM versus pretreatment isolate IC50 = 0.0064 microM). Neither the increased sensitivity to itraconazole nor the decreased activity of fluconazole on the growth of the relapse isolate results from changes in the intracellular content of these agents. To reach 50% inhibition of ergosterol synthesis in both the parent and relapse isolates, about 2 nM itraconazole was needed; with fluconazole, 50% inhibition was achieved at 20.9 microM and 55.5 microM, respectively. Resistance to fluconazole may develop during treatment and results from decreased sensitivity of ergosterol synthesis.     

Vermicompost extracts influence growth,mineral nutrients,phytonutrients and antioxidant activity in pak choi (Brassica rapa cv. Bonsai,Chinensis group) grown under vermicompost and chemical fertiliser

BACKGROUND: Multiple studies have been reported on the effect of compost tea on suppression of certain plant diseases. However, relatively little work has been done to investigate the effect of vermicompost tea on yield and nutritional quality of vegetable crops. In this study, experiments were conducted to determine the effect of extraction method on vermicompost tea quality and subsequent effects on growth, mineral nutrients, phytonutrients and antioxidant activity of pak choi plants grown under organic (vermicompost) and synthetic (Osmocote) fertilisation. Three vermicompost teas obtained by different extraction methods, namely non‐aerated vermicompost tea (NCT), aerated vermicompost tea (ACT) and aerated vermicompost tea augmented with microbial enhancer (ACTME), were applied to the plants. Aerated water served as control. RESULTS: Mineral nutrients were significantly higher in ACTME compared with other teas, but total microbial population and activity did not differ with extraction method. All vermicompost teas similarly enhanced plant production, mineral nutrients and total carotenoids, and this effect was most prominent under organic fertilisation. Antioxidant activity and total phenolics were higher under organic compared with synthetic fertilisation. Vermicompost teas generally decreased phenolics under organic fertilisation and increased them under synthetic fertilisation compared with the control. CONCLUSION: The effect of vermicompost tea on crop growth is largely attributable to mineral nutrient, particularly N, uptake by plants. Non‐significant differences among extraction methods on plant response within fertiliser regimes suggest that aeration and additives are not necessary for growth promotion and nutrient quality under the conditions reported here. Copyright © 2009 Society of Chemical Industry